The goal of the proposed research is to identify the causes of two characteristics of the specific-language impaired (SLI) children found in preliminary research: a generally slower mastery of new morphemes and a specific morpheme accessing deficiency; and by doing so, illuminate the nature of their language-learning problem. A series of studies is proposed that addresses both of the characteristics. The general approach proposed in this series of studies is to teach a group of SLI children a set of invented language morphemes and the solutions to certain conceptual problems to determine whether the unusual way they learn language is a reflection of general rule-induction or specific language learning capacities. This comparison is made within two groups of SLI children who have different kinds of language impairments, and in all cases their performances will be compared to those of normal language-learning children who match the impaired children on age or language development. The central question that is addressed is whether the unusual language-learning patterns of SLI children have specifically perceptual, linguistic, or broader cognitive explanations. Four related projects are proposed: the first compares concept and linguistic rule learning, the second compares the performance of two subgroups of SLI children on morpheme-learning tasks, the third examines the instructional effect across different linguistic elements, and the fourth examines the effect of phonological salience on morpheme learning.